Transmission Fluid

If you get a whiff of burning transmission fluid, be advised it is definitely not the sweet smell of success. That's because it may indicate your transmission is overheating. Transmission fluid not only keeps the transmission's many moving parts properly lubricated, but it prevents the unit from burning itself up, by providing much-needed cooling.
In some vehicles, the transmission even has its own mini-radiator (an oil cooler) that circulates fluid to transport heat away from the transmission unit itself.
Common causes include low or inadequate transmission fluid, which can in turn indicate a leak or dirty fluid that needs changing.
If you thought your transmission was safe from wear at least while it was in neutral, the truth might surprise you. Look to the next page for the scoop on noises in neutral.


-Courtesy of How Stuff Works